smb: client: reduce stack usage in smb_send_rqst()

Clang warns about exceeded stack frame size

  fs/smb/client/transport.c:420:1: warning: stack frame size (1048)
  exceeds limit (1024) in 'smb_send_rqst' [-Wframe-larger-than]

Fix this by allocating a structure that will hold transform header and
compound requests.
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/transport.c

@@ -416,13 +416,19 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 	return rc;
 }
 
+struct send_req_vars {
+	struct smb2_transform_hdr tr_hdr;
+	struct smb_rqst rqst[MAX_COMPOUND];
+	struct kvec iov;
+};
+
 static int
 smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 	      struct smb_rqst *rqst, int flags)
 {
-	struct kvec iov;
-	struct smb2_transform_hdr *tr_hdr;
-	struct smb_rqst cur_rqst[MAX_COMPOUND];
+	struct send_req_vars *vars;
+	struct smb_rqst *cur_rqst;
+	struct kvec *iov;
 	int rc;
 
 	if (!(flags & CIFS_TRANSFORM_REQ))
@@ -436,16 +442,15 @@ smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 		return -EIO;
 	}
 
-	tr_hdr = kzalloc(sizeof(*tr_hdr), GFP_NOFS);
-	if (!tr_hdr)
+	vars = kzalloc(sizeof(*vars), GFP_NOFS);
+	if (!vars)
 		return -ENOMEM;
+	cur_rqst = vars->rqst;
+	iov = &vars->iov;
 
-	memset(&cur_rqst[0], 0, sizeof(cur_rqst));
-	memset(&iov, 0, sizeof(iov));
-
-	iov.iov_base = tr_hdr;
-	iov.iov_len = sizeof(*tr_hdr);
-	cur_rqst[0].rq_iov = &iov;
+	iov->iov_base = &vars->tr_hdr;
+	iov->iov_len = sizeof(vars->tr_hdr);
+	cur_rqst[0].rq_iov = iov;
 	cur_rqst[0].rq_nvec = 1;
 
 	rc = server->ops->init_transform_rq(server, num_rqst + 1,
@@ -456,7 +461,7 @@ smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 	rc = __smb_send_rqst(server, num_rqst + 1, &cur_rqst[0]);
 	smb3_free_compound_rqst(num_rqst, &cur_rqst[1]);
 out:
-	kfree(tr_hdr);
+	kfree(vars);
 	return rc;
 }